Differential gear



E. DE H. CALDWELL.

DIFFERENTIAL GEAR. I APPLICATION FILED MAY 20, I918.

Patented Dec. 6, 1921.v

Illll 3 vwe w rm 7 Edwin pelkwnkzaiwell i aflo no,

ear tries.

DIFFERENTI L GEAR.

specification of Letters Patent.

Patented Dec. 6, 1921..

Original application filed July 14,1917, Serial No. 180,523. Divided andthis application filed May 20,

" 1918. Serial No. 235,434.

To all 107mm it may concern.

Be it known that I, EDWIN DE HAVEN CALDWELL, a citizen of the UnitedStates, residing in the town of Dun-kirk and county of Chautauqua, Stateof New York, have invented certain new and useful Improvements inDifferential Gears, of which the following is a specification, referencebeing had to the accompanying drawings, illustrative of one particularembodiment of my invention.

This invention relatesto devices known as differential gears or balancegears, such as are used in the transmission of power to. a divided shaftwhen it is desired that the two parts shall turn at the same ordifferent speeds under varying conditions.

More especially the invention relates to such devices as are used inconnection with the driving axle of vehicles where the device well knownhas a differential gear, transmitsthe power from the driving shaft tothe driven shaft or axle, the latter being made two parts and adjacentends being driven in a manner permitting their rotation at differentspeeds or the same speed, so that when turning corners the wheels of thevehicle may each roll at the proper speed while the power is transmittedto them equally. In this construction of differential, the aim of thisinvention is to provide means whereby the power will-be transmitted toone wheel in case the opposite wheel loses traction or purchase on theground, and to accomplish this object automatically.

The particular embodiments of my invention herein shown and described,are specific forms of my invention set forth in my pending applicationfor -United States Letters Patent, Serial No. 180,523, filed July 14,

1917, entitled Differential gears, of which this application is adivision; and the specific forms to which this application relates areshown in embodiments in the accompanying drawings, in which- Figure 1 isa plan view of a bevel gear differential.

Fig. 2 is an elevation of the balance gear parts of Fig. 1, assembledwith frame and driving gear.

In the form shown in Figs. 1 and 2, the general elements of a bevel geardifferential are shown, but without regard to exact dimensions, such asthe eccentricity or other features. In this embodiment the two drivenshaft parts NN have gears M keyed or splined thereto, each engaging,respectively,-bevel pinions OO. In the'ordinary differential these bevelpinions O O' would be one and the same instead of two, and wouldaccommodate freely anyrelative movement in opposite directions of theaxle gears N-N. By separating the bevel pinions into two, and makingthem two complete gears, I add a means of controlling the rotation ofthe two gears under unusual conditions. That is, by the plate P with abearing at either end engaging the eccentric hub portions 00' of thegears O--O, like rotary movement is permitted of the gears O() inunison. If, however, the resistance to rotation on either one of thegears is materially greater, that is the relative resistance materiallygreater, or a sudden impulse on one, the eccentric link connectionbetween the bevel pinion hubs would have to drive the other bevelpinion. However, whether differential action will ensue de pends Whetherthere is suflicient power trans mitted by the link from the one pinionto the other, and on account of the eccentricity it would mean the powerwould have to be sufiicient at the very small relative radius toovercome a larger resistance. 'Beforethe force transmitted through thelink is suflicient to cause this transmission of power,

the force of the driving system of the car has exceeded the powernecessary to turn the driving wheel still having-traction, or, in otherwords, the power has been sufficient to propel the vehicle before itreaches the critical )Olllt of transmittin motion from one of thepinions to the other. Thus automatically in those unusual cases whendifferentlal action is not wanted, my differential box will not function-but as soon as a sub stantial balance of resistance is restored as instraight running of a car with both wheels having substantially equaltraction, the balance is such that the differential will function.

Thus action of one of the bevel gears having an eccentric associatedportion engaging an interconnecting element of the differential in whichit is eccentrically mounted, will cause a locking of the interconnectedelement of the differential, when there is a substantial disturbance ofthe balance of resistance between both sides of the dilierential. Itwill be noted that in the embodiments shown, one form involves the application of the eccentric locking elements in c connection with themounting ofthe pinions of the differential, while in the other form theeccentric mounting is on one of the'differential gear rings. 7 i

Various modifications may be made with respect to the arrangement ofparts and dimensions to effect the results aimed at in myinvention,-ancl the construction may be simplified for the purpose'ofits application to various designs, but in thisapplicationthe embodimentof my invention in bevel gear transmissions is shown, although inprinciv ple it may be otherwise used.

What I claim and desire to secure by Letters Patent is: g

A diiferential gearing having relatively rotatable coaxial gears, aframe rotatable about the axis of said gears, pinions, journaled on theframe and engaged with said gears, eccentrics rotatable with saidpinions, and a link having bearings engaging said eccentrics. y a c c iIn testimony whereof, I have signed my name to this specification, inthe presence of two subscribing witnesses, this 16th .day of May, 1918.

i EDWIN de HA'VEN CALDWELL.

Witnesses:

O. F. Harms, I HERMANN F. Conn.

